The present disclosure relates to a capture basket system for an underdeck pipehandling machine. More precisely, the present disclosure relates to a capture basket system for use below an underdeck pipehandling machine on a drill rig, where the capture basket system includes a capture basket that is designed to retain a falling object such as a pipe.
An “underdeck pipehandling machine” refers to machines positioned in and below a drill deck on drill rig such as a single or multi hole mousehole or an in-deck tong.
When handling pipes in an underdeck pipehandling machine, experience shows that a danger of dropping pipes during operation exists.
A pipe or stand dropped into a mousehole or by an underdeck handling device has the potential to cause significant damage to life or property. If the dropped object is able to fall into the ocean it also has the potential to cause catastrophic damage to well head equipment.
Mouseholes are sometimes provided, with an internal energy absorbing system which is sized to handle dropped pipes/stands. Due to the high kinetic energy involved, these devices are generally for once-only use.
In the case of an internal or integrated energy absorbing system, this force would normally be transferred, to the deck or other supporting structure via the structure of the mousehole/pipe handling device. In this case, the accidentally dropped object loading would become a load case for the structural design of the mousehole/pipe handling device.
This is not an optimum situation because the accidental load may be greater than the normal operating load cases.
Designing the mousehole/pipe handling device to withstand these loads, even assuming that the elastic limits are exceeded, may be extremely difficult and may result in weight/cost penalties.
The deceleration distance is of paramount importance in the design of any energy absorbing system. The longer the deceleration distance, the lower the force applied.
Therefore, from the point of view of structural design, a “long” energy absorbing system would generally be preferable to a “short” system. However under deck devices are often in conflict with other equipment/operations such as blowout preventers (BOPs), Christmas tree handling, and the like.
This means that the structural requirements may often be incompatible with the physical layout requirements.
U.S. Pat. Nos. 3,527,319 and 4,982,813 explain safety and safety shock absorbing nets. However, these are not capable of retaining a killing pipe of the kind associated with drill rigs.
U.S. Pat. No. 6,024,383 discloses an energy absorbing means that includes an energy converter for use in vehicles where a tubular converter body is deformed. GB Patent No. 2,011,019 shows a kinetic energy absorber where a tube is permanently deformed by a movable carriage, U.S. Pat. No. 6,338,399 discloses an energy absorption device that includes a sleeve through which a bolt head is drawn.